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    chan025's Avatar
    chan025 Posts: 3, Reputation: 1
    New Member
    		  
    #1

    Nov 11, 2008, 06:33 PM
    Theremostat volt reading
    Thank you HVAC1000. I took your advice and jumped the thermostat terminal from R and W. The heat had started. Right now, I replaced the thermostat but I have one question to ask you. When I set it to heat, after the furnace has been turned on, I checked on the PC board between C and W and I read only 2or3 volts. Isn't it suppose to be reading 24 volts because the heat is running?
    mygirlsdad77's Avatar
    mygirlsdad77 Posts: 5,713, Reputation: 339
    Plumbing Expert
    		  
    #2

    Nov 11, 2008, 06:38 PM

    Curious
    hvac1000's Avatar
    hvac1000 Posts: 14,540, Reputation: 435
    Heating & Air Conditioning Expert
    		  
    #3

    Nov 11, 2008, 09:01 PM
    Isn't it suppose to be reading 24 volts because the heat is running?

    NO it will not read 24 volts since the circuit is already complete.

    You posted to a different location than your original post. Confusing to all of us. Post on the same thread as the original from now on. Glad you got it going.
    KISS's Avatar
    KISS Posts: 12,510, Reputation: 839
    Uber Member
    		  
    #4

    Nov 12, 2008, 08:30 AM

    Mmmm: R and W; V= ~0 when on
    ... C and W; V = 24 V when on

    Between C & R; 24 V all the time.

    There is a typo or misread. Between R & W is a contact and therefore it will read 0V when closed and likely 24V when open.

    Since W makes a connection to R, and between R and C there is a transformer, the voltage between C and W will read 24 V when the furnace is on and 0V when it is not.

    Furnace on should read call for heat.
    KISS's Avatar
    KISS Posts: 12,510, Reputation: 839
    Uber Member
    		  
    #5

    Nov 12, 2008, 08:30 AM

    Mmmm: R and W; V= ~0 when on
    ... C and W; V = 24 V when on

    Between C & R; 24 V all the time.

    There is a typo or misread. Between R & W is a contact and therefore it will read 0V when closed and likely 24V when open.

    Since W makes a connection to R, and between R and C there is a transformer, the voltage between C and W will read 24 V when the furnace is on and 0V when it is not.

    Furnace on should read call for heat.
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